The four male performers in Lucy Guerin's Untrained have to be changed at unusually regular intervals: the work's premise is to put two entirely novice dancers onstage with two professionals. For Guerin's funny, charming and often revealing material to make sense, that encounter has to remain fresh, and freshly challenging.

As soon as the cast present themselves on stage at the Purcell Room, it's clear where the divide falls. Mike has the paunchy belly of a man who works at his desk, Jake is neater but tends to fidget in the spotlight. It's Ross and Alisdair who communicate the physical assurance that speaks, instantly, of seasoned performers.

Guerin's strategy is to put the four men through a sequence of movement tasks and observe the ways they navigate them. A wheeling phrase of hip-hop, a slice of martial arts, some pirouettes, highlight how drastic the difference can be – in suppleness, rhythm and co-ordination – between the two pairs. Yet while the struggles of the amateurs are inevitably comic, Guerin is far from staging a joke at Mike and Jake's expense. Both men are beguilingly game and honest, as are the two professionals, and the work shifts very cleverly to show us the emotional as well as the physical dynamics of the group: highlighting the competitiveness that goads Ross and Alisdair to out-jump and out-spin each other, the laconic wit with which Mike makes comic capital of his awkward bulk and works his way into the audience's cheering affection.

Sections in which the dancers talk about themselves and their bodies add colourful brushstrokes to this group portrait: as do elements of improvisation that take them to the brink of helpless laughter. In Untrained Guerin opens intriguing views of human nature as well as of the human body.

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